Hello. i need to purchase one driver to fit 4 led lights to. the spec on the LEDS are; 5.5W, 350mA please can you help

You need to work out if yours are constant current or constant voltage.

Traditional/professional LED fittings will be constant current, and wired in series with a constant current driver.

Many new fittings are constant voltage, with fittings wired in parallel.  In this case you do not have a driver, you have a transformer.

350mA is the rating of many constant current drivers, which leads me to suggest you need a constant current type, but do check!

For 22 watts of lighting, this would do: http://www.cp-lighting.co.uk/ELT-25W-350mA-Constant-Current-LED-Driver?gclid=Cjw...

You MUST ensure your fittings are wired in SERIES (red to black, red to black etc), otherwise you risk damage!